Implementation of South Sudan s 2018 peace accord has stalled and authorities have blocked humanitarian access to areas where conflict has restarted, the UN panel of experts said in a report seen by Reuters on Thursday.
They also said there was a lack of transparency in how the government collected and spent oil and other revenues.
The government disputed the findings, saying agencies had access to all areas and it was working to fix the economy.
Oil-rich South Sudan erupted into civil war soon after securing independence from Sudan in 2011, leading to an estimated 400,000 deaths and one of the worst refugee crises on the continent since the 1994 Rwandan genocide.
A fragile peace accord between President Salva Kiir and former rebel leader Riek Machar was agreed in 2018 and they formed a government of national unity in February, setting the stage for potential peace.
But since then implementation has "mostly stalled, as the signatories have failed to adhere to the deadlines set in the peace agreement and have backtracked on aspects of its political, security and economic provisions," the panel said.
As fighting has erupted in areas across the country, the panel found that South Sudan People s Defence Forces and National Security Service "routinely blocked the United Nations Mission in South Sudan and peace monitors from accessing conflict areas".
The panel also noted that the government, which relies heavily on oil for its revenue, has turned to resource backed loans and contracts as it struggles to plug a budget deficit projected to hit $700 million.
Deng Dau Deng, the deputy minister of foreign affairs, said the panel of experts themselves had been allowed entry into South Sudan, which shows "that the government of South Sudan is committed to meet the UN resolutions on South Sudan".
"South Sudan is cooperative," he told Reuters on Thursday. "The UN mission in South Sudan (UNMISS) and other agencies have full access to all the areas."
He also said, without providing details, that his government was working to improve the deficit situation in the country.